Re: Tequila

Re: Tequila

I can answer that. Bartholomew Sykes was an English scientist who developed a proof ascertainment system which later was used to announce proof strength on whisky and other spirits labels. Under his sytem, alcohol spirits were considered proven, i.e., of sufficient strength, at 57.1% ABV. He ascertained this by burning mixtures of gunpowder and alcohol, at 57.1% ABV the mixture flared adequately in his view. To this proven strength he assigned arbitrarily the number 100. Pure alcohol or 100% ABV was however in his system 175 proof, not 200 proof as in the more logical U.S. system, and thus termed 75 overproof (75 OP in the old labelling). E.g., 70 proof is 30 underproof (30 UP) and this equates (when you examine conversion tables) to U.S. 80 proof. You can use a rule of thumb that for every number of Sykes proof over or under 100 this represents 1/2% alcohol by volume but this is approximate only apparently since conversion tables I have consulted show e.g., 70 Sykes proof as 80 U.S. proof (not 84 proof or 42% ABV: 57%-15%=42%). The Sykes system was adopted by the United Kingdom, its former colonies, and other countries within the U.K. trade orbit or otherwise in its influence. In the early 1980's, the Sykes system of announcing alcohol content was abandoned in the U.K. in favor of the European Union norm which uses the Gay Lussac system which measures alcohol by the volume of ethanol in the container. The suggestion (or rather query) is whether some countries, perhaps smaller ones where change proceeds slowly, may still use the Sykes system for the labels of whiskey and other spirits. Unless the alcohol by volume content is also shown on the label there is no way to know without consulting its applicable laws.